java charat函数用法_Java String charAt()用法及代码示例

Java String charAt()方法返回指定索引处的字符。索引值应介于0到length()-1之间。签名：

public char charAt(int index)

参数：

index- Index of the character to be returned.

返回：

returns character at the specified position.

异常：

StringIndexOutOfBoundsException- If index is

negative or greater then the length of the

String.

例：展示charAt()方法的用法原理

// Java program to demonstrate

// working of charAt() method

class Gfg {

public static void main(String args[])

{

String s = "Welcome! to Geeksforgeeks Planet";

char ch = s.charAt(3);

System.out.println(ch);

ch = s.charAt(0);

System.out.println(ch);

}

}

输出：

c

W

// Java program to demonstrate

// working of charAt() method

class Gfg {

public static void main(String args[])

{

String s = "abc";

char ch = s.charAt(4);

System.out.println(ch);

}

}

输出：

Exception in thread "main" java.lang.StringIndexOutOfBoundsException:String index out of range:4

at java.lang.String.charAt(String.java:658)

at Gfg.main(File.java:9)